Riki Nendou, one of the main characters, is a dutiful and dull-witted boy. He likes helping people and aiding the weak, and though his silliness annoys his classmates, his motives are mostly well-intentioned. His appearance is made very distinctive by his exotic haircut and oddly defined chin Riki is sinister in appearance, so most of his classmates avoid him, assuming he is a bad person. His defining physical attribute is the scar on his left eye, something that can be used to differentiate between him, his father, and his mother, who all have the same faces. His hair is cut like 7 cm cut in the middle and the rest untouched with his mohawk like hair colored yellow while the rest is black. In school, he wears the standard PK Academy uniform but keeps his uniform open, showing an orange t-shirt. Outside school, he mostly wears collared shirts. He has a moustache, which he originally grew to match the moustache of his favorite comic book villain, Baron Cola. Riki's dominant trait is his apparent lack of intelligence. He has bad manners and typically needs things to be explained to him countless times, then still cannot understand them.

a romantic and dreamy girl who has had a lot of painful love experiences. Chiyo is a petite girl with chin-length orange-brown hair tied with a pink hairband. She has wide, honey-coloured eyes. In school, she wears the standard female uniform of PK Academy Chiyo is a romantic girl who would do anything for love, as proven by her many attempts to get Saiki Kusuo to notice her before moving on to Takeru. After breaking up with Takeru, she starts chasing Kusuo again only to later fall for Shun instead (with the help of Kusuo). However, due to the instability of her feelings towards boys, it is no surprise when Mikoto states that she will become a 4-time divorcee. Despite her faults, Chiyo is still a good person and cares deeply for her friends.

has all kinds of psychic related abilities. He usually tries to avoid getting involved in problematic or attention-grabbing situations, but his attempts always end up going wrong or having unusual ends to his displeasure. His trademark appearance contains his constant frown, his green-tinted glasses and two pink antennas located slightly above each ear, which have the function of limiting his power. Initially he was always seen alone, but in the course of the story he develops lasting friendships with his classmates and schoolmates average build and height. He has short hot pink hair, fair skin, and pale purple eyes with no signs of pupils nor emotion. Kusuo wears a pair of controller devices, one on each side of his head, which are never removed except in situations of absolute necessity or by accident. The devices resemble white, cyan antennae, with pink, lollipop-like spheres, Kusuo wears white glasses with lime green lenses to prevent his petrification power. Kusuo is a reticent, self-centered, reclusive shut-in who hates being the center of attention he is quite reserved and rarely uses his voice, instead preferring to project his words via telepathy into the minds of others. To avoid interactions, he tries to make other people disinterested in him or avoid others as much as possible.

Teruhashi Kokomi is a Class 3 student. She is globally considered to be the perfect, beautiful girl, with people stopping and staring upon seeing her. Kokomi is a love interest of Saiki Kusuo, constantly seeking his attention due to his skeptical nature. Kokomi is a slim girl of average height with a pale complexion. She has long, dark blue hair that flows past her shoulders, with bangs framing her face. Her eyes are round and blue with a downward slant. A golden, occasionally rainbow, aura surrounds her most of the time. Kokomi is considered very attractive, being the most beautiful girl in the world Kokomi considers herself both beautiful and kind. Although her thoughts make her appear overconfident, hubristic, or conceited, she is simply self-aware.

Kaidō Shun is classified by his classmates as a chuunibyou. He calls himself The Jet-Black Wings and thinks that the world and its events are overseen and controlled by an Evil Organization called The Dark Reunion. Because of this, he is an outcast within his class. Shun likes to show off, but he often becomes cowardly in dangerous situations. When push comes to shove, however, he will endanger himself for those he cares about his hair is spiky and he wears contact lenses. In reference to his chuunibyou, he wears red bandages on both arms to seal away his ‘powers’. He is the shortest boy in his class, standing shorter than most of the girls as well.